Abnormalities of membrane phospholipid content have been found in subcellular organelles from the Morris 7777 hepatoma. Studies are proposed to examine other transplantable hepatoma lines to see if the disturbance is a general phenomenon in malignant tumors or a specific defect in one type of tumor. Experiments will be carried out to see if reduced microsomal phospholipid content leads to secondary declines in the activity of certain phospholipid-dependent enzymes in the Morris 7777 hepatoma. Human tumor membrane phospholipids will also be studied when available.